Purpose: Microscopic Imaging Module Vision scientists have used optical imaging to assay function at a variety of length scales - from subcellular processes to collections of cell organized into networks. With the advent of new fluorescent probes and imaging technologies, the possibilities of both measuring and manipulating cells and circuit function are more powerful than ever. Two notable breakthroughs in the past few years have revolutionized the ability of vision scientists to manipulate and probe excitable cells in intact tissue. First, the development of two-photon microscopy allows for the stimulation of fluorescent probes deep in tissue with a minimum amount of phototoxicity. Second, ion channels have been engineered to open and close in response to light, allowing for spatially localized stimulation and/or silencing of individual cells with millisecond time resolution. The vision science community at UC Berkeley is unique in that several of its members have been at the forefront of developing and utilizing these and other new optical technologies that are revolutionizing vision research. UC Berkeley is also fortunate in having several advanced microscopy systems on campus. In particular, the Molecular Imaging Center (MIC) in the LSA building has five confocal/2-photon imaging systems, a spinning disk confocal system with a spatial-light-modulator used for optical excitation, and soon-to-be installed PALM microscope for super-resolution imaging, all designated for shared use.